A method for parametrizing integrated circuits is disclosed, for example, in DE 195 48 984 A1. The parametrization process adjusts and customizes an integrated circuit after the integrated circuit is manufactured or when the integrated circuit is mounted on circuit boards. The integrated circuit must be adjusted or customized in order to initialize and/or set specific values for certain circuit components of the integrated circuit, such as an identification value of the respective integrated circuit. For example, the integrated circuit may include an oscillator whose clock frequency must be set to a predetermined frequency. In addition, certain properties of a digital/analog or analog/digital converter incorporated in the integrated circuit may also be set by the parametrization process.
It is also known to use a so-called “Zener zapper” for parametrizing integrated circuits. The Zener zapper, however, requires that the integrated circuit has a relatively large number of terminals. Zener zapping is difficult to control and offers few programming choices. Moreover, the Zener zapper cannot be used to parametrize the integrated circuit during assembly. Alternatively, the integrated circuit may be parametrized by applying a certain bus protocol to separate terminals. The approach also requires a relatively large number of additional terminals and therefore increases the manufacturing cost of the integrated circuit. Incorporation of additional terminals may also cause reliability problems of the integrated circuit.
Finally, the integrated circuit can be parametrized by using special serial protocols. Such serial parametrization protocols, however, are very susceptive to errors. In addition, the bus protocols must be synchronized with the oscillator frequency of the integrated circuit. The special serial protocols also impose more stringent timing requirements.
It is therefore desirable to provide a method for parametrizing an integrated circuit without requiring additional terminals in addition to those already provided for normal operation. It is another object of the invention to provide an integrated circuit for carrying out the method.